The invention relates to a motor vehicle with a lowerable roof construction and, more particularly, to a motor vehicle with a lowerable roof construction having at least a roof part and a rear part. The roof part is swivellable about a roof swivel axis of the rear part by means of a forced control device in a defined relative movement with respect to the rear part. The rear part is able to swivel about a rear swivel axis which is fixed to the vehicle.
In the case of a motor vehicle according to German Patent document DE 40 10 276 A1, it is known to lower a roof construction, having a roof part and a rear part, into a space located behind the motor vehicle passenger compartment. This space is closed by a covering flap. In this case, the roof part serves for closing a remaining roof opening between a rigid rollover frame. The rear part serves for closing a rear window opening remaining between the lateral frame parts. The roof part is connected by hinges at its rear edge region--viewed in the travelling direction of the vehicle--to the upper edge of the rear part. This is done so that the roof part can be swivelled in relation to the rear part. Consequently, the roof swivel axis of the roof part is located on the rear part transversely with respect to the longitudinal axis of the vehicle. The rear part itself is able to swivel about a rear swivel axis fixed to the body of the vehicle. The roof part is guided in the region of its front edge by guide elements in guide rails of the lateral frame parts. These guide elements are coupled to the swivel drive of the rear part so that when the rear part swivels, the roof part is in each case swivelled along with it in a defined relative movement. For a motor vehicle in which the entire roof structure is lowered behind the vehicle seats of the passenger compartment, so that a true convertible is produced, this forced control of the relative movement of the roof part and rear part is not suitable. In the case of such a convertible motor vehicle, there are no lateral frame parts in which the roof part could be guided.
There is therefore needed a motor vehicle of the above-mentioned type in which the roof construction is able to be lowered completely in a manner which corresponds with a true convertible, while nevertheless ensuring a defined relative movement between the roof part and the rear part when the roof construction swivels.
These needs are met according to the present invention by providing a forced control device having at least one control element. The control element is connected in the region of the roof swivel axis in a rotationally fixed manner to the roof part and interacts with at least one further control element which is fixed to the bodywork in the region of the rear swivel axis. The forced control of the relative movement of the roof part and the rear part of the roof construction, i.e., a two-part hardtop, ensures that no uncontrolled movements can occur during opening and closing of the roof. This forced control has the advantage that gusts of wind or inadvertently driving with a roof which, although closed, is unlocked, cannot result in any damage. In addition, the roof construction can be handled in a simple and obvious manner, so that operating instructions can be minimized.
In a preferred embodiment of the invention, the rear part in the region of the rear swivel axis is assigned a torque-compensating mechanism for producing a defined torque characteristic during the swivelling movement of the roof construction. As a result, the swivelling of the roof construction can take place by a defined torque characteristic, so that compensation for the weight of the roof construction occurs independently of the respective swivel position.
In a further preferred embodiment of the invention, a pull rope which acts on the rear part at a distance from the rear swivel axis is provided. The pull rope has a spring characteristic and is articulated in a manner such that it is fixed to the vehicle. The pull rope is deflected by a contoured pulley which is rotationally fixed to the rear part and maintains a perpendicular distance between a line of spring force action of the pull rope and the rear swivel axis during the swivelling operation of the rear part. In this case, the contour of the contoured pulley is determined by the spring force and by the perpendicular distance between the line of spring force action and the rear swivel axis required for the torque to be applied.
In a yet further embodiment of the present invention, the control elements of the roof part and the rear part are frictionally or positively interconnected by an endless rope pull or chain pull. Swivelling of the rear part therefore inevitably effects a corresponding swivelling of the roof part about the roof swivel axis of the rear part.
In a still further embodiment of the invention, at least one control element has a roller which is movable about an axis of rotation parallel to the roof swivel axis. The roller is offset by a small distance into the rear part and is connected by means of a lever linkage in a rotationally fixed manner to the roof part. This roller is likewise connected by means of a rope pull or chain pull to the control element which is fixed to the body work and is on the rear swivel axis.
In a yet still further embodiment of the invention, the control elements of the roof part and of the rear part are connected by a rack-and-pinion drive which absorbs tensile and compressive loads.
A further embodiment of the invention, provides at least one crank arm mounted at a distance from the rear swivel axis in a manner such that it is fixed to the bodywork. The free end of the crank arm acts at a distance from the roof swivel axis on a lever continuation connected rigidly to the roof part.
In another embodiment of the present invention, two swivelling side parts of the roof construction, in particular two rear side windows, which can be lowered together with the roof construction, are coupled by a coupling device to the swivelling movement of the rear part of the roof construction. The swivelling-in of the side parts of a lowerable roof construction in a motor vehicle is already known from German Patent document DE 39 03 358 A1. In this case the side parts are held in slotted link guides of the roof part and are swivelled inward during the substantially horizontal displacing of the roof part. However, in the case of the present invention, such slotted-link guides in the roof part are not necessary. The swivelling-in and out of the side parts is advantageously derived from the swivelling movement of the rear part.
In a further embodiment of the invention, each side part is held on a swivel arm at a distance from its swivel axis. The swivel arm is mounted rotatably about its swivel axis in a mounting fixed on the rear part of the roof construction. In a further embodiment, a coupling element, which is articulated in a manner such that it is fixed to the bodywork, is coupled to the swivel arm and turns the swivel arm in dependence on the opening or closing movement of the rear part. Consequently, a forced control of the relative movement between the side part and the rear part is achieved.
This forced control is achieved in the case of a further embodiment of the invention by the swivel axis of the swivel arm being assigned a coupling element which interacts positively or frictionally with a counter-element which is fixed to the bodywork and is coaxial with the rear swivel axis.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.